Engine power control apparatus



Sept. 30, 1952 s, R

ENGINE POWER CONTROL APPARATUS 4 Sheets-Sheet 1 Filed April 4, 1946 I llllllllJ 5 TEPMEW C 7 Sept. 30, 1952 CRUM I 2,612,226

ENGINE POWER CONTROL APPARATUS Filed April 4, 1946 4 Sheets-Sheet 2 INVENTOR.

srsms/v c/ rzm Y BY Spt. 30, 1952 s. GRUM ENGINE POWER CQNTROL APPARATUS 4 Sheets-Sheet 3 Filed April 4, 1946 INVENTOR. STEPHL'N C/il/M Sept. 30, 1952 s, CRUM 2,612,226

ENGINE POWER CONTROL APPARATUS Filed April 4, 1946' I 4 Sheets-Sheet 4 (a/P5017577? WWW-056K555 llfiI/II-WAD PRESSUIYE- M. //G. 170.9.

INVENTOR. JTEP/lE/V 6mm @wwu INTO/WW5) Patented Sept. 3O, 1952 ENGINE POWER CONTROL APPARATUS Stephen ,Crum, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., acorporation of Delaware Application April 4, 1946, Serial No. 659,651

33 Claims. (Cl. 170-43534) The present invention is concerned with engine power control apparatus and more particularly with that of the type in which a single lever is employed to adjust the manifold pressure and the setting of a propeller governor and toposition a throttle valve.

It is customary in connection with an airplane to have a propeller governor for maintainingthe propeller at any desired speed. Normally, manual means are provided for adjusting this propeller. The throttle of the engine is normally operated by a throttle lever entirely independently of the means for adjusting the propeller governor. In addition, where a supercharger is employed for compressing the air supplied to the engine at higher altitudes, it is customary to provide a control system for maintaining any desired pressure within the induction system of the carburetor or the intake manifold. A manually operable adjusting device is normally provided for varying this pressure. Where the airplane is a, multi-engine aircraft, the pilot is compelled to adjust individually the various propeller governors, to separately position the throttles for the various engines and to adjust the control system for the superchargers to maintain the desired manifold pressure. The present invention is concerned with control apparatus in which a single manually operable control associated with each engine, which may be the regular throttle lever, positions the throttle, adjusts a manifold pressure control system which controls both the throttle. and the regulator for the supercharger, and also adjusts the propeller governor to maintain a propeller speed desirable for the manifold pressure which is selected.

An object of the present invention, is, accordingly to produce an improved engine power con trol in which the various factors affecting the engine power can be adjusted by a single lever.

More specifically, an object of the present invention is to provide a manually operable device for operating the throttle through a lost motion connection with automatic means for adjusting the throttle within the range of the lost motion.

A further object of the present invention is to provide in such an arrangement means for adjusting the automatic means by the manual means to maintain a desired manifold pressure.

A further object of the invention is to provide such an arrangement in which the lost motion between the manual control and. the throttle varies with the position of the manual control so that despite said lost motion, the throttle is returned to closed position upon the manual control being returned to its minimum power posi tion. v

A further'object of the present invention is to provide engine power control apparatus in which a manually operable member positions the throttle and varies the setting of a pressure controlling means to control both a throttle and a regulator for the supercharger and in which in dependent means is provided for varying the setting of the pressure controlling means to cause only the throttle to be operated by the manually operated member. 1

A further object of the present invention isto provide an arrangement in which there is a single manually positioned member for adjusting both the propeller speed and a pressure responsive impedance network for controlling the manifold pressure in which independent means is provided for varying the pressure setting of the impedance network to vary the relationship between the pressure being maintained and the propeller speed.

A further object of the present invention is to provide an arrangement such as set out in the previous objects in which both the control point and the sensitivity of pressure control are varied by the manually positioned member.

A further object of the present invention is to provide in an engine power control apparatus a novel means for checking the propeller governor by running the throttle motor to open position.

A further object of the present invention is to provide an engine power control apparatus of the type discussed above in which means is provided for adjusting the manifold pressure rela- -tive to the propeller speed for any setting of the manually positioned member and in which means is provided for rendering the adjusting means inefiective when the manually positioned member is moved to a position calling for the maximum normal amount of power.

A further object of the present invention is to provide in throttle positioning mechanism, a manually operable member for moving a throttle at a non-linear rate in accordance with the non-linear change of flow with change in position of the throttle, said manually operable member also controlling the setting of a condition responsive system controlling a motor so as also to position the throttle at a non-linear rate.

A further object of the present invention is to provide in a power control apparatus, electrical means for positioning the throttle and a regulator for a supercharger, manual means for positioning a throttle in the event of failureof electrical power, and an air motor for position- 3 ing the supercharger regulator in the event of such an electrical power failure.

A further object of the present invention is to provide a novel linkage mechanism in which the lost motion between two members is variable depending upon the relative position of one of the said members.

A further object of the present invention is to provide an engine power control apparatus in which novel means is provided for checking the action of the magnetos, the engine, the propeller governor and the control apparatus.

Other objects of the invention will be apparent from a consideration of the accompanying specification, claims and drawing, ofwhich:

Figure 1 is a schematic view of my control apparatus shown in connection with an aircraft,

Figure 2 is a horizontal plan view ofcthe coordinating unit of my apparatus with portions shown in section,

Figure 3 is a vertical plan view of the'cam mechanism of the coordinator unit with theelements in their minimum power or idle position,

Figure 4 is a view similar to that of Figure 3 but with the elements in the positions which they assume when manually moved to their maximum power or military power-position,

Figure 5 is a plan view showing the throttle cam and an associated linkage in an intermediate manual position with the elements shown in a different relative position in dotted lines,

Figure 6' is a plan view similar to that of Figure 5 with-the elements shown in solid lines in the relative positions in which they are shown in dotted lines in Figure 5 and with the elements shown in dotted lines in relative positions which they-assume when the manual, operatoris moved in a' direction to close. the'throttle. v

Figure 7 is-a chart; showing graphically the relation between manifold pressure propellerspeed, throttle position; andposition of the manual operator, and

Figure 8. is a view-of. a modified form of pressure controller cam-and associated lever shown in an intermediate position.

Referring to Figure 1, the reference numeral I0 is employed to indicate a radial'aircraft engine having aplurality of radially disposed cylinders ll'each connected to an intake manifold I 2 and an exhaust manifold I 3. exhaust manifold 13 is conducted through an exhaust conduit l lto an exhaust gas turbine 15 having a turbine wheel IS. A nozzle ring H is adapted to discharge the exhaust gas in such a manner as to impingethe buckets of the turbine wheel [6 to cause rotation of the latter. The conduit-l4 terminates in a discharge duct .or outlet 19 in which is located a damper like valve 20 commonly referred to as a wastegate. Asthe waste gate is opened, the gases may flow past it with less resistance than presented by the turbine so that the gases are by-passed around the nozzle ring and the operating-speed of the turbine is reduced. As the Waste gate 20 is closed, more and more of the exhaust gas is forced throughthe nozzle ring IT to increase the speed of the turbine.

The turbine I5 is connected through a gear box to a supercharger 26. The supercharger is. of the centrifugal type in whichthe extent of compression of the air. is varied in accordance with its Gas from the i cooler, the air is delivered through a carburetor intake duct to a carburetor 3|, where the compressed air is mixed with fuel. The air then passes through a further supercharger 32 which is driven directly by the engine It. The air then flows through the intake manifold l2 to the various cylinders.

Referring back to the intercooler 29, this comprises a means for removing the heat of compression from the air leaving the supercharger 26. The intercooler comprises a plurality of conduits 34' through which the air is passed and which are disposed in heat exchange relation with air introduced into a scoop 35 and passing through a conduit 36.

Referring to the carburetor 3|, the carburetor is entirely conventional and the only element thereof which is of importance as far as the present invention is concerned is the throttle 3'! which is operatively connected to a bell crank 38 which upon being rotated in a clockwise direction moves the throttle towards'open position. The throttle is shown in the drawing in substantially full-closed position.

The engine I0 drives a variable pitchpropeller 40 having a plurality of blades 4| and-t2. The pitch'of these blades is controlled by a propeller governor 43 of conventional'form. The propeller governor is provided with adjusting mechanism 44 including a pulley drum 45. Aspring is shown as extending between the fixed portion'of the adjusting mechanism 44 and a point on the pulley drum'45 such as to bias the drum to-a position'at which the propeller is set to maintain a speed desirable for cruising. This speed, for ex ample, may be between 1800 and 1900*R. P. This spring is normally located within the adjusting mechanism but is-shown here as an'external spring to implify the illustration.

The apparatus described so far, in itself, forms no part of my invention. The apparatus of the present invention is concerned with controlling an airplane engine of the type just described. In generaLI provide a coordinator unit 50,'a-pilots control panel'53, and a Waste gatemotor 54. The coordinator unit is manually adjusted by means of a conventional throttle lever 5!, which maybe positioned in the same location as the conventional airplane throttle. lever. Upon actuation of this lever, the position of the throttle is directly varied and at the same time,'the setting of a pressure responsive device 52 is varied. The pressure responsive device throughan electrical network to be described, controls the operation of a throttle motor 53 which also positionsthe throttle. The pressure responsive mechanism 52 also controls through an electrical network, the waste gate motor 54 to position the waste gate-20. As will appear from the later description, .the throttle motor '53 and the waste gate motor 54 are sequentially operated so that the throttle is gradually moved to open position and the waste gate is thereafter moved to closed position. The movement of lever 55 also serves "to vary the setting of the propeller governor adjustingmechanism 4 3 to maintain a propeller speed corresponding to the selected manifold pressure. The pilots control panel '53 broadly provides means for varying the manifold pressure for any given setting of the throttle lever 5 I- and for performing certain switching functions incidental totesting of the operation of the engine. The various units of the control apparatus will now be describedin more detail. a 1

Referring to the coordinator 56, thisis shown in greater detail in Figures 3 to 6 and will be decoordinator will be briefly described at the presenttime in connection with Figure 1. Referring to Figure 1, this is shown as comprising a central shaft 58 to which is secured an input crank arm 59. The crank arm 59 is connected to the throttle lever 5| by any suitable linkage. As illustrated', a link 60 extends between the crank arm 59 and a downwardly extending arm of a bell crank lever 62. The bell crank lever 62 has a horizontally extending arm to which is secured a further link 63 which is pivotally connected to an arm 64 integral with the throttle lever 5|. It will be apparent that as throttle lever 5| is moved in a clockwise direction, the shaft 58 is likewise moved in a clockwise direction-as indicated by the arrows adjacent that shaft. The shaft 58 has secured to it a triangular crank arm 65 which cooperates with a link 66, the link 66 being in turn pivotally secured to a crank arm 6! secured to a shaft 68. Also secured to the shaft 58 are cams I2 and I3. The cam I2 is employed to adjust the propeller governor and will be referred to as the propeller governor cam. The cam I3 is employed to adjust the pressure controller 52 and will be referred to as the pressure controller cam. The details of the pressure controller are described and claimed in my copending application for Pressure Responsive Device, filed concurrently herewith. For a more detailed understanding of the operation and construction of the pressure controller 52, reference is made to the aforesaid application. This apparatus is, however, shown schematically in sufficient detail in the present application for a complete understanding of my invention.

- Referring to the mechanism including the triangular crank arm 65, this mechanism positions the shaft 68 to which the crank arm 61 is conneoted. The shaft 68 functions to position the throttle, a throttle crank arm 80 being secured thereto. Secured to the throttle crank arm 80 is a cable 8| which passes over idler pulleys 82, 83 and 84 and is connected to the-bell crank 38 in v such a manner that movement of the crank arm 80 in a clockwise direction causes movement of the throttle 31 towards open position. It is to be understood that while I have shown a cable 8| connecting the crank arm 89 to the throttle, a link-age mechanism may be employed where desired.

The shaft 68 is also .positioned by the throttle motor 53. This motor comprises a rotor 81 with which are associated field windings 88 and 89. The rotor 81 is connected through a reduction gear train 9| to a shaft 92 which is connected through a strain release clutch 94 to the shaft 58. The strain release clutch 94, which is shown in more detail in Figure 2 is shown schematically here as consisting of two members 95 and 96 spring pressed into engagement with each other by a spring 91. The member 95 is provided with a cam surface having a depressed portion 98 into which a corresponding portion of member 96 moves. By reason of this depressed portion 98 in the cam surface of member 95, the members 95 and 96 tend to be held together in a fixed driving relationship with respect to each other. It will be obvious, however, that upon the torque tending to affect relative rotation of shafts 68 and 92 exceeding -a predetermined value, relative movement of the shafts will occur by reason of mem- :ber :96 sliding on shaft 68 and rotating with respect to member 95.

Securedto the shaft 92 is a slider 98 which cooperates'with two resistors 99 and I00. The resistance value of resistor 99 is relatively large as compared-with that of resistor I00.

Referring now to the triangular crank arm 65, this crank arm carries two rollers |0I and I02. The roller I0 2 rides within a slot I03 of link 66. while the roller IOI cooperates with a curved cam surface I04 and a'horn I05 of link 66. The parts are shown in the position they assume when the throttle lever 5| is in its minimum power position. Asthe throttle lever 5| is moved to the right to cause clockwise rotation of shaft 58, as previously explained, the roller IOI bears against the horn I05, moving link 66 upwardly and rotating shaft 68 in a clockwise direction. The resultant clockwise movement of the throttle crank arm 80'wil1 cause throttle 31 to be moved towards open position. As the. clockwise movement of shaft 58 continues, the roller IOI will ride outwardly on the horn I05. Just as the roller I0| leaves the horn I05, the roller I02 comes into engagement with the end of slot I03. During the further clockwise rotation of shaft 58 and lever 65, the roller I02 remains in engagement with the upper end of slot I03 and transmits movement to link 66 by reason of such engagement. Upon reverse movement of the throttle lever 5| and consequently of crank arm 58, assuming that the shaft 68 tends to remain in the position to which it has been moved, the roller I02 is moved into engagement with the lower end of the slot- |03 and moves the link 66 by reason of such engagement. As this counterclockwise rotation continues, roller I0| is brought into engagement with the cam surface I04, rollin On the cam surface in the direction of the horn I05. The final movement of link 66 is caused by the'coaction between roller |0I and curved surface I04. By the time that the shaft 58 has been rotated back to the position shown in the drawing, the roller I0| will have moved over this curved cam surface to the position shown in which it is in engagement with the horn IOI. In the above described operation, the effect of the throttle motor 53 on the position of shaft 68 has been entirely neglected. The effect of the throttle motor 53 on shaft 68 will be described in more detail in the section in the specification headed Operation. At this time it may be briefly pointed out, however, that during an intermediate range of positions of shaft 58, an appreciable amount of lost motion exists between triangular crank member 65 and the shaft 68 as will be explained in connection with Figures 5 and 6. It is thus possible for the throttle motor 53 to variably position the throttle within this range of lost motion.

The propeller governor cam I2 is provided with a cam slot ||0.- Disposed within this slot is a roller I I I secured to crank arm II2 which in turn is secured to a shaft to which is rigidly'secured a pulley drum II3. A cable H4 is looped over pulley H3 and pulley 45 of the propeller governing adjusting mechanism 44, the cable 4 passing over idler pulleys I I5 and H6. The cam slot IIO extends inwardly from its right-hand end, as shown in the drawing, towards the center acrea e 7 12 i is rotated'lin clockwise direction, the crank arm H2 is first rocked in a counter-clockwise direction until the roller III is adjacent point a. .Thereafter,.the crank arm-I I2, isfrotatedin a clockwise direction .to the end ofthe range of movement. of cam 72. The initial counterclockwise movement of-lever, II2 causes a corresponding movement-of the pulley II 3 and hence of pulley 45 of the adjusting mechanism for the propeller governor. This initial movement of pulley 45 in a clockwise direction will'he against the effect of spring 48.- As the rotation of cam 12 continues to cause clockwise movement of crank arm H2; the pulley 45 is rota-ted in .a clockwise direction, whichrotation is assisted by spring 48. Atthe time that the'roller III passes a point I), the pulley 45' will be in the position to Whichit is biased by the spring 48." Thereafter, the continued clockwisemovement of pulley45 Will be in'a direction to oppose the action of spring 48. v

-Av spring II has one end thereof securedto the pulley III and the other-end thereof secured to-a support I I1, which may be adjustable. The support III is so disposed with respect to roller I II and the'aXis of crank'arm- I I2 thatiwhen-the roller III is adjacent point 12 of the cam slot III), .the roller. I I I, the pivot point of crank arm H2, and the point of attachment of spring II5 to support I I! lie in'a straight line. Because of this disposition of spring H5, the spring II5 will tend to rotate thecam 72 until the roller III is ad jacent point a. From there until the roller III reaches point I), the spring I I 5 will oppose movement of cam I2. At point b, the sprin II5 will go 1 over center and thereafter will assist in further clockwisemotion of cam 12. It. will be recalled that when the roller -III is adjacent point b'OII cam I2, the pulley 45 is in the position to which itis biased by spring43, this position corresponding to the normal optimum cruising speed. While the cam I2 is'being rotated. from the position shown to the position in which roller I II is adjacent point a, pulley 45 is being rotated in a' counterclockwisedirection against the biasing'actio n of spring 48. During this movement, the'spring ,I I5 is assistin in the rotationof cam 12. The spring II5 thus opposes the action of spring 48 and hence aids in the movement of cam 12, 'While the roller III is passing from point a to b, the pulley 45 is being rotated in a clockwise direction and is being assisted in such rotation by the spring 45. During the same movement, the spring I I5.is opposing the movementof cam 12. Again, the two springs oppose eachother so that the movement of cam I2 is relatively unaffected by the two springs. When theroller III is moving between point D and the left-hand end of cam slot II 0, the spring 48 is opposing the movement of the pulley 45, while the spring I I5, having passed over center, is aiding in the movement of cam 12. Thus, again the two springs oppose each other. The result thus, of the spring H5 is to oppose the biasin effect of sprin 48 and to cause the movement of cam l2i'to be relatively unaifected by; this spring 48. If the cable II4 should accidentally be broken, spring 43 will be effective to automatically move the .pulley45 to the normal cruising speed, in the. manner which is oldin such propeller governors. Thus, the spring II5 effectively counteracts the action of spring 43 as-far as the action of the coordinator .50 is concerned without eliminatingthe usual desirable function of spring 48 .in.the.event of a failure. of the mechanism 8 for positioning thepulley 45 of the prop governor adjusting mechanism. i

The pressure controller cam I3 i provided with a cam slot I25. Cooperating withthis cam. slot I is a' roller I26 secured'to a crank armlzl. The crank arm IZ'I is in turn secured to gear I28which meshes with a second gear I29. Secured to gears I28 and I29 and rotatabletherewith are spring supports I30 and HM, respectively. The outer end of a spring I32 is secured to theouter end" of spring support I30. while the outer end of a spring I33 is secured to the outer end of spring. support I3I. The innerends of springs I32 and I33 are secured to-a yoke member I34 which is secured to a stem member I35. The stem'member I35 is positioned bya bellows member I36 which is securedto the lower end of stem I35. Bellows member I30 is located within the'housing I31. Surrounding the lower portion of stem I 35 and forming an air tight seal between the bellows I36 and the wall'of the opening through housing I37 through which stem I 35 extends, is a second bellows member I39. A conduit I40 extends between the bellows housing I31 and the intake manifold I2 and serves to cause intake manifold pressure to be applied to the exterior of bellows I 36. The bellows I39 not only serve as a sealing member but also serve to compensate the action of bellows I33 inaccordance with changes in atmospheric pressure due to changes inaltitude of the aircraft on which the apparatus is installed. The function of bellows I30 in this respect will be discussed later.

The stem I35 is employed to position a wiper I of a potentiometer I46. Potentiometer I46 comprises, in addition to the wiper I45, aresistance member I4! with which the wiper slidably engages. Connected across theterminals ofresistor I4! is ajsecondary I50 of a transformer I5I. The primary of the transformer is designated by the reference'numeral I49. The network formedbytransformer I5I and potentiometer I46 is referred to generally by numeral I48. The wiper I45 is secured to a gear I 52 which meshes with a rack I53 formed in the stem I35. It will be obvious that downward movement of stem I35 will cause a clockwise movement of gear I52 and hence a clockwise movement of wiper I45 with respect to resistor I47. Conversely, an upward movement of stem I35 will cause a counterclockwise movement of wiper I45. An increase in the manifold pressure causes bellows I36 to be compressed to cause stem I 35 to move downwardly and cause such a clockwise movement. Thus, on an increase in manifold pressure, the wiper I45 is moved downwardly with respect to resistor I47 While upon a decrease in manifold pressure, the slider I45 is moved upwardly. The-force against which the manifold pressure acts is determined by springs I32 and I33 and a further calibrating spring I57. The spring I51 is fastened at its lower end to the upper endof stem I35 and at its upper end-to a threaded spring retainer I58 which extends through a fixed support "and is adjustably retained in place with respect to said support. For any given adjustment of spring retainer I58, the force exerted by calibrating spring I51 remains constant. The efiect of. springs I32 and I33 is, however, varied in accordance with the position of crank arm I 2'! which in turn, of course, is determined by the position of cam 73. As cam I3 is rotated, the. radia1 distance of roller I26 with respect to the center of rotation of 9 cam. 13 increases as it follows the cam slot I25. This causes a counterclockwiserotation of the crank arm I21. Sucha counterclockwise-rotation of crank arm I21 causes'the spring supports I30 and I3I to be rotated in a counterclockwise and in a clockwise direction, respectively. In other words, the outer ends of the spring supports I30 and I3I are swung toward each other. This affects the action of springs I32 and I33 in two ways. In the first place, as theouter ends of the springs are swung toward each other, the resultant of their force parallel to the axis of stem I35 is increased so that they exert an increasing effectupon stem I35 tending to move the same upwardly. At the same time, the effective spring rate is also increased. In" other words, a much greater force is required to move the stem, I35 through a predetermined distance. Theeifect of this operation is more fully describedin my copending application on. Pressure Responsive Device referred to above. The effect of this will also be discussed in more detail later in this application. I a

The position .of stem I35 is also affected by a leaf spring member I60. which bears against the collar on stem I35 and hasv twoarms adapted to lie in the path of spring supports I30 and I3I when the latter members are rotated apart to a predetermined position. Upon the. spring supports I andI3I engaging the leaf spring member I60, further movement of the spring supports apart from each other forces the stem I downwardly by reason of the force directly exerted between the spring supports and the stem through the leaf spring I60. The function of this will likewise be discussed in moredetail later.

Also secured to the crank arm I21 is a cam 162 which cooperates with a slidablevpin I63v constituting the actuator of a snap switch, shown schematically in the drawing as" comprising a switch blade I64 biased into. engagement with one fixed contact I65 and: movable. with a snap action into engagement with a second. fixed'contact I66. The cam I62 is provided with'a rise which begins at point I10.which is spaced-from the point of contact with pin I63 shown in the drawing by an angle of approximately Upon rotation of the crank arm I21 in a counterclockwise direction, the cam will be effectivelafter approximately 45 degrees of movement. to cause switch blade I64 to be moved with a snap action from engagement with contact I65 into engagement with contact I66.

Referring again to the throttle motor 53.111 19 1 winding 88 is connected to two line wires HI and I12 leading to a suitable source of alternating voltage such as an inverter (not shown). Line wire I1I is connected to. the upper terminal of winding 88 by a;conductor .I14,,condenser I15, and conductor I16. Line wireI12is connected to the lower terminal of winding 88 by a conduc-v tor I11. The condenser I15, functions to shift the phase of the current through field winding 88 by approximately 90. The, other field winding 89 is connected to the output terminalsofan amplifier I18. The amplifier is of any suitable type in which th phase of the output voltage is re-.

versible with a reversalinthe phase-of the input. voltage. Atypical amplifier of this type is shown in the co-pending application of Albert P. Upton, Serial No. 43'1,56 1', filed April 3, 1942. The power input terminals of the amplifier. are connected by conductors. I19 I12, respectively. The amplifier is provided with two signal input terminals I8I and I82; the 18.13?

ter of which is connected to ground at I83.. The

and I80 to line wires. HI and input terminal I8I is connectedby conductors I84 and I85 to the left terminal of resistor I00. A transformer l 81 is providedwith a secondary winding I88 and a primary winding "I49. 1 The left-hand terminal of secondary winding I88 is connectedby conductor I90 to the left-hand ter-' minalof resistor 99. The left-hand terminal of secondary I88 is also connected through a resistor I92 of relatively high'resista'nce value and conductors I93 and- I84 to the input terminal f I8I. The right-hand terminal of secondary I88 isconnected by conductor l96'to the right-hand terminal of resistor I00. The right-hand terminal of secondary I88 is also connected through a relatively high resistor I to ground at I96. The

transformer I81 together with slider 98 and resistors 99, I00 and I92 constitute a follow-up network referred to generally .by thenumeral I98.

The function of this networkiwillbe discussed In any event, since the apparatus depends upon the proper phase relationshipbetween .the.var-.-

ious voltages, it is essential that they all be connected to, thesame power source. To'illustrate this, thesame reference characteris being ap- I pliedtothe primaries of all of the various trans-Q for'mersit being understood that if desired, these:

various transformers may becombined intoa relativelysmall number of transformers. ..The'y.- y are shown as separate transformers in the illustration merely for convenience-in illustration;

.The-waste gate motor assembly 54 comprises a motor:200,having arotor. 20I and field windingsv 202 and 203. vWinding. 202 is the line winding of motor 200 and is connected to line wires HI and I12 by conductors 204, 205 and 206 and by a con denser 201. Like condenser I15 in connection with motor 53,.condenser 201 is effective to shift the phase of the current supplied to winding 202v by 90. The winding 203 is connected by. conductors 209 and 2I0,to the output terminals of an amplifier 2I.I1;. This amplifier may be similarin general construction toamplifier I18. Infact, the two amplifiers may form two portions of a twogangamplifier. The power input terminals of the amplifierare connectedby, conductors 2I2 and 2 I3 to the line wires HI and I12. .The amplifier .2II ,isprovided with two input terminals.

2I4 and 215., Thelatter terminal is grounded at 2- I6. e

; Themotor 200' is operatively connected through I a gear traing2l1 to a shaft 2I6. Secured to the shaft2I8 is a crank arm 225. This crank arm is connected by a link .220 to the wastegate20. It will; be apparent that clockwise movement of crank arm 225 is effective to move waste gate .20

towards closed position and, conversely, counterclockwise movement of crank arm 225 causes an opening movement of waste gate 20. Stopsare providedto'limit the movement of crank arm 225,, the stop limiting the opening movement being indicated by numeral 223.

An airkturbine 238 isa'lso associated with the waste gate motor 54.. This turbine issupplied with 'air'from the discharge conduit. 28 of compressor 26under the control of a pressure relief valve 231 connected on its inlet side to the conduit 28 and connected'on its outlet side to the air turbine 238. Also associated with the crank arm 225 is a stoparm 224 biased in wast'e'gate closing. direction. Th'e movernent of the stop will be briefly referred to. later infthis specifica-.

Alsossecured to shaft 2 l8 isra sliderl2i9 which cooperates with aMresistor 222' of a follow-up po-' tentiometer-22i. The slider '2l9 is connectedby conductor 242300 the input terminal 2M.

A transformer 23:3 comprises a primary: I49,

and. a secondary winding 3234,, this secondary winding :being' provided with two taps 235'and 2361; .The resistor .222pis connected across the right-handportion of secondary 234' betweenth right-hand end thereofandtap 236. .The leftehand portion of secondary winding.

234?..between theleft-hand thereof. and tap 23:5

is :c.onn'ected across a resistor. 22 1 forming, a portion of overspeed.potentiometer.228.. The overspeed potentiometer 228 comprises a wiper-.229

which moves: over resistor 22.1... At one .end of the resistor? 221,- there is a. conductive bar 23.0 .with. whichthe wiper .229 is normally in engagement.

Anoverspeedzcontroller 21M)v is. connectedby a.

shaft- 24l' to the gearbox..25= so. as. to be driven at, aspeed dependent uponthe. speed of theturbine 1.5.; The; apparatus 240 is designed so that whenever .the speed. exceeds a.. predetermined value, thewiper 229' is moved to the. left as long as the speed remains; above that. value. controller of this. type'is shown in. the patent to Daniel G. TayloryNo. 2,388,350, issued. November 6,1945; The. transformer 233 and the potentiometers 22l'- and 22!!- together constitute a rebalancing .and overspeed inetwork referred to generally :by. numeral 231:."

The: pi-lots' control. unitx53xwill now be describedl' This unit. generally consists of a pluralit'y' of networks including manually adjustable resistors which are used for calibration and for selection ofmanifold pressures which are differ ent'. from thoseautomatically: obtained by the. manipulation of the. throttle. The networks are generally referred to: by the reference numerals 23311,:2-3911,2400 2401); 24111;, 241b, 243'- and 244';

Whilethe. details of.- these networks and the manner of their association .inthemselves form norpart. of my invention, being claimed in theco-pending application of Alex B. Chudyk for EngineControl: Apparatus, they are- 7 described here in order to providean understanding of the operation-of the entire apparatus. The control panel. is-shown asdesigned for use-in: connection with a two engine airplane I although "it can ob viously beemployed, by-duplicating cert-ainelements, with airplane having any-number of engines.- The-networks 289m 240a and 24111; are-- associated withflthe control mechanismjof the engine illustrated in the drawing; The-identi= calnetworks 239b, 24Gb.- and 24'! br are adapted to be connected into the .compound network, of a control apparatusfor another engineof the same airplane. The bridges 243 and 244...ar.e- ,pro-

vided for makingsimultaneous adjustment of the operation of all of the engines. v

Network 239acom-prisesa. potentiometer 246' consisting of a resistor 24'! over which moves a manually. positioned, wiper; 248. A transformer 25 o,-comprise.s a: Primary winding. 14a and a..sec.-:.

An overspeed.

a second pair; of fixed, contacts 259 and 260.

The network 248-aconsists of a transformer 2G2 and apotentiometer 263. The transformer262 comprises a primary, 149 and a secondary wind-- ing 264.'The potentiometer 253 consists of a resistor 266 over which moves a wiper 281. The opposite terminals of resistor 286 are connected between the lower.v terminal of's-econdary 264 and an intermediate tap 261s. 1 1

Network 241a consists of a transformer 21!! and apotentiometer 212.. The. transformer 218 consists of a primary Winding i 49 and a secondary winding 213. The potentiometer 212 consists: of. a. manually positioned wiper-214 which movesover. a resistor. 215, the opposite. terminals of which are connected to the opposite terminals of. secondary 213 .of transformer 218. Since the networks; 23912, 2482) and 24th are identical to the networks 239a, 240a and. 24m, it is be-.:

lieved unnecessary .to describe these latter net-5 works in-detaih. Similarly, the switch 255b connected betweennetworks 2351b. and 241011 is identi -I calto switch 255a. and hencealso nee'd not'be described;

The network: 243'. incl-udesa transformer 215 having a primary winding 149 and. a-seconda'r'ywinding. 216. Connectedacross the terminals of secondary 216i.is;aresistori211; also constitutingpart of the network243. A slider 218 moves. over resistori21l: and a bar 219 of high conductivity which. constitutes a continuation. of resistor 21'!- beyond; the. upper-terminal of resistor v21 1 which isconnected. to-secondary 2.118... Thus,.upon slider 218 moving oventhe conductive bar '219, it re'-' mains atzthe. same potentialas the: upper endof secondary 21.6.

The network, 244; consists. of. a transformer 280 and apotentiometer having a. resistor 28! The transformer: .280. consists: of a primary winding I49 and-a secondary winding'282'. The secondary winding1282= has .a, plurality of taps283- and 284. The resistor 28! is connected between the upper terminal of secondary 282 and the'tap 284. A- bar 286 of. high conductivity is connected tetheend of'resistor'28 l2 beyond thepoi-nt to which it isconnectedto: tap 284;... A wiper 281 moves over resistor 281 and conductive bar 288. The two wipers 218: and. 28.1; are connected together physically so as to move. inuunisom'al'though being electrically separated byinsulating material 289. While the two-sliders 218 and 281 are being moved through the: range of. movement in which slider 218contacts resistor 211 the normal control range), the slider: 28.1 is'moving' over the conductive bar. 286 andlremaining at-thepotentiaLoftap 284.

Ayswitch: 290' is associated with the network 244. This :switch'; "which -wilI be referred tolateras. an. engine: check switch comprises a switch blade '29l :biased into engagement with a fixed contact 2921 The switch-blade 28! isa'ctuated by a push button and movable into engagement withza second fixedcontact293. The-'contact'292' is connected to the slider 281' 293sisconnected to the-lower-end of secondary 282; The

Whilethecontact' switchblade 2'91ffisx-connected to ground 1'3 Inthe preceding-description, the sturcture of the coordinator 50 has been briefly described on the basis of the schematic showing of. Figure 1. As previously indicated-this coordinator. unitis shown in more detail in Figures 2-6. At this time, these figures will be described. It is to beunderstood, of course, that the elements in Figures 2-6 will be indicated by the same reference characters as Were'employedin connection with Figure 1.

Referring first to Figures 2 and 3, the various elements of the coordinator mechanism are either located within or secured to the outside of a house ing 305 consisting of two sections 306 and 301 which are removably fastened together-by any suitable fastening means 308. The shaft 58, to which the input crank arm 59 is secured,'is rotatably supported in two tapered roller bearings 309 and 310, located in the'housing sections 306 and 301, respectively. The opposed tapered roller bearings are provided because they are able to withstand the vibration to which the coordinator unit is subjected by reason of engine vibration. The throttle crank shaft 68 is mounted at its outer end in a similar tapered bearing 3| I. At its inner end, it is disposed within a ball bearing, the retainer only of which is shown and designated by numeral 312. Bearing 312 is supported by the cam member 95 and a. collar member 315 rigidly secured to the motor shaft 92 of motor 53. The collar 315 is secured in'driven relation to the motor shaft 92 and is fastened to the cam member 95 so that the cam member 95', the collar 315 and the motor shaft 92 revolve together. A nut 316 is secured to the extreme inner end of shaft 68 to retain shaft 38 in place with'respect to bearing 312. The throttle crank arm 80 is rigidly secured'to the throttle shaft 68 and is held in place by a nut 318. A stop arm 319 is interposed between the crank arm 80 and a shoulder on shaft 68 and cooperates with any suitable adjustable stop means (not shown) to limit the travel of the throttle crank shaft 68. A collar 321 is secured to shaft 68 so as to be nonrotatable with respect to the shaft. A hub portion of crank arm 61 surrounds an inwardly extending shank portion of collar 321. The crank arm 6'1 is held against rotation with respect to collar 321 by stud screws 323, only one of which is shown in the drawing. Secured to crank arm 61 is a pivot pin 324 which extends through a bearing 325 located within a bearing retainer" 326 secured in the end of link 66. Link66, in turn, cooperates with rollers 101 and 102 carried by crank arm 65 secured to shaft'58, as best shown in Figure 3. While bearing 325 is'shown for purposes of illustration as a sleeve bearing,'any suitable bearing, such as opposed ballbearings. may be employed.

slidably supported on shaft 68 by a bearing 330 is a roller carrying shaft 335. Disposed on the right-hand portion of the shaft, as shown in Figure 2, are two rollers 336 and 331. Similarly disposed on the left-hand side are two rollers 338 and 339, which are shown only in dotted lines. The outer rollers 33'! and 338 bear upon a cam surface of cam 95. The inner rollers 336 and 339 are slidably disposed within a slot'340 of a sleeve 341 secured to collar 321 so as to be rotatable therewith. The spring 9'1, referred to in connection with Figure 1, bears against the arm 335' and urges rollers 331 and 338 into engagement with the cam 95. A numeral 343 is employed to designate the cam surface of cam 95. It will be noted that this cam surface rises to a high point half way between the location of rollers 31;] and 338 amazes 14 when they are in the position shown in the drawing. In other words, the rollers 331 and 338: are shown in the low point of the cam. This is-the positionto which they tend to move by reason of thebias applied by spring 91. Upon the torque v between motor shaft 92 and the throttle crank .arm shaft 68 exceeding a predetermined value,

the rollers 33'! and 338 are forced to ride upwardly on the cam surface 343 so as to permit relative movement between shafts 92 and 68. Upon the rollers 331 and 338 moving with respect tothe cam surface 343, the roller carrying shaft 335is forced outwardly, the rollers 336 and 339 rolling on the walls of slot 340. This actiontakes place against the biasing action of spring 91. It will be readily apparent that the roller carrying. arm, the cam 95, and the spring 9'1 form a strain release connection which permits motor shaft 92 to drive throttle shaft 68 as long as the force resisting the rotationof throttle crank shaft 68 does not exceed a predetermined value. It is also to be understood that the roller carrying arm 335 corresponds to the member 96 in the schematic showing of Figure 1.

The triangular crank arm 65 which carries rollers 101 and 102 is secured to a collar member 350 which is rigidly secured to shaft 58 so as to be rotatable therewith. Relative rotation between crank arm 65 and collar 350 is prevented by a plurality of screws 351 (shown in section in Figure 3) extending between the two members.

The shaft 58 extends through apertures in the earns '12 and '13. The cams '12 and '13 are held'against the collar 354 by means of a plurality of screws 355 (only one of which is shown). The collar 354 is nonrotatably secured in any suitable fashion to the shaft 58. A dowel 356 extends through the cams '12 and 13, the collar 354, the collar 350, and a cam 65 to hold all of these members against relative rotation with respect to each other and with respect to the shaft 58.

The roller 111 which cooperates with the cam '12 is journaled by any suitable bearing means on a pin 358 which extends through the outer end of crank-arm 112. Crank arm 112, is, in turn-rigidly secured on a shaft 360 which is journaled in opposed tapered bearings 362 and 363 housed in a hub member364 secured by screws 36'! (only one of which is shown) to the housing member 306. Rigidly secured to the outer portion of shaft 360 is the propeller cable drum 113 which is held in place by nut 368 threadedly secured to the outer end'of shaft 360. The nut 368 serves to clamp together in assembled relation on shaft 360, the cable drum 113, the crank arm 112, the bearings 362 and 363 and a collar 310 interposed between crank arm 112 and th inner race of bearing member 363. I

Only a fragmentary portion of the exterior of the pressure controller 52 is shown in Figure 2. The pressure, controller is secured to the rear wall of housing section 306 beneath the electric motor 53. As shown most clearly in Figure 4, the crank arm 12'1- is adjustably secured to a shaft 3'15 extending into the pressure controller (not shown in Figures 3 and 4). This crank arm 315 carries the roller 126, schematically shown in Figure 1 and best shown in Figure 2'.

Reference will now be made to Figures 3 to 6 in which the relative positions of the various camelements and crank arms associated therewith are illustrated. As previously indicated the elements are illustrated in Figure 3 in the position they assume when the throttle lever is in the fullyretarded or idle position. The elements 15 occupy the same .relativeposition: in this view as they do in the :"schematic .showingof :Figure. 1.. Referring first 'to itheitrian'gul'ar. crank Jarm 165 the dink :66, and the: crank. arm: 6] secured: to shaft-.88; it willfbe noted. that the .roller I I z is inlengagement with .the baseof the-horn I65 and that: the; roller. I02: occupies a position .1 a. little morethan' oneethirdihe.distanceniislot :I I33v from thelile'ft-h'and :end' thereof.

Referring. inextt 130112118. propeller :governor scam I2;;"it -will be-notedtthat the rotlerz'l I Ifis' att-the' right-handaend of' the slot I It. Securedxto ith'e pizi1353ic'arrying: the-roller 'I I I .isxarrarm 3.891160 which-issecuredione end .of ithe spring; I 'I I'he opposite end of 1 the spri'ng ;.is :secured -i to; a. ipin. H I extending through aboss: 382 formed: in the housingsection 366: The pin III *iseheld in place by'a stud screw 53831 It isvto. becnoted thatwvithrthe roller IIIin'the positionshown; the taxis: of cranka I I 2- :lies: .on-ra line :With spring, I I 5.: Thus,- upon :the- :slightest .-rotation of: came I2 :in aw-clockwise direction-to rockithe lever-I I2: in -acounterclockwise: direction, the-spring; H5. is effective to bias the/crank a-rm..for;-rotation inthat direction.

Referring to the pressure controller cam 13; the: roller. I26 is shown in the extreme left-hand end of the-slot I;

Theelements'ra're'shown in Figure-4 after the throttle lever has been moved. through almost its entire range of movement. It is assumed that the motor 53 has remained deenergized throughout this range of movement so that the movement of the throttle crank arm. shaft 68has been against the-action of. the-strain release connection provided by'cam. 95 and the roller carrying arm 335. It will be noted that the roller-IN carried by the triangular crank arm 58--is: completely/separated from the horn. I65 and that'the roller I02 is in engagement with the left-hand endof slot I03 'of crank arm 66. Duringtthe final phaseof the movement of -the triangular crankarm-65, link.66' is:moved entirely by reason ofxen'gagementof roller I62 with the left-hand end ofthe slot Ill-3. As aresult ofthe rotation of crank arm 65, the. crank arm fitsecured to thethrottle crank shaft 68 has been rotated from the'position shown in Figurex3 tothatshown'in Figure 4; The propeller-governor cam I2 hasbeen rotatedto apoint such V thatthe'roller III is-adjacent the left-hand end of'theslot H0. In doing this,,crank arm II2 was rocked first" inxaicounterclockwise direction with the'aid of spring II5v until roller III-was adjacent the point a -of the cam slot H6; crank arm H2 was then: rockedin a=clockwise direction against the biasing action of spring H5 until roller III was adjacentthepoint' b of the cam slot H9. At this-pointthe axiswof rotation of crank arm :I I2 wasagain in line with the axis .of. spring 1 I5 so that the spring exerted notendency'to. rota-tecrank arm H22 Uponfurther movement :of-cam I2, the spring I I5 assisted the clock-wisemovement of crank arm H2 anchas shown in Figure 4; the/spring II5-is definitely biasing the crank H2 in a clockwise direction. The iunc-tionof-spring,H5 has been explainedin connectior-rwith Figurel It will be recalled that this-spring is employed to neutraliz e the action of the-internal biasing springv 1 ofthe conventional propeller governor sothat the movement-cream I2 and henceof thecoordinator input shaft 58 is-relatively;-smooth and does not require varying amounts of force for.

its operation. as would. bathe-case tif rsometmeans The T6 for: compensating. for :the biasing effect of the propellerr'biasing. spring; were not employed.

With. the-:pressure:controller'cam 73 :in the position .shown. in: Figure 1.4, theroller' E26 iszadjae cent .th'el'ight-hand end of the: slot I 25. In this position; the crankarm'xl 21 'isrQcked to substantiallyiits' extreme counterclockwise position. In movingto. this'position, the crankarm was rotated int a. counterclockwise direction, while-the camz13 wasrbeing rotated from the position shown imFigure 3 to one in which the roller I26 had left'theinwardly curved left-hand portion of slot I25. Thereafter, as the roller I26 rolled along thezfirstzportion ofthe long intermediate part of slotzI26, the rotation .of crank arm I21 was relatively small. As the-rotation of camfl3 contimiedxsocsthat the :roller- I26 traveled down the finalportion of themain portion of cam slot I26, the crank;arm I 21 was again advanced reaching its maximum position with the cam I26'in the inwardly curved right-hand end portionkof slot I25; The result of thisrmovement of crank arm I2], asbestindicated in the chart of.-.Figure 7, is s'to cause an initial .rapid 'rise in the manifold pressure,.aperiod'during which the 'manifold pressure. is maintained. relatively, constant, and a final period in which: the manifold'pressureis gradually: raisedsto its; maximum value The :action of the throttle crank arm positioning mechanism is .best shown .in Figuresafikandfi; In. Figure 5; the crank-arm 65, the: link. 66 and the crankarm 67 aresh'own in an inter-mediate position to which they havebeen manuallymoved byactuation of theainput shaft 58. Itxwill be noted'that the roller 'IOI is; just leaving thetip;

ofthehorn I05 and. that the roller I fl 2xhas en-L gaged:theleft-handend:ofslot I03. Upon con tinued clockwise movement of shaft 65, the .lil'lk 66eis moved by: reason of roller 162 bearing-against this: left-hand-end. of slot I03; It is also to be noted that at this time. a large .amount of lost motion exists between crankarm 65eand'link 66.. When the elements. were in the position shown in Figures land-3, corresponding to. the closed position of the throttle, the roller: II was disposed; between the: horn H15 and the inclinedcam surface- I04.- Consequently, it was impossibleato. move. link I 66 .in "anyxlirection with respect to-crankarm- 65; As soon as the roller IU'I tends-:to-move-out on "thehorn I65; anvincreasing amount of alosttmotion rispermitted; 'Before'athe roller IIH has reached the position shown in'Figure .5, the lost motionibetweenlink' 66 andcrankarmw-65 corresponds-substantially tothe full length-of -slot-I 63-.

To il-lustrate -thee-action of .the throttle :motor irrtaking :up thislost motion between link. .68 and crank arm 65, the elements have been-shown: in Figure; "5 in :dotted lines *in the positions" to which they have been moved :by; the throttle motor drivingo'shaftxfl2 tin rotatingcthecam member 98'. It willbesnotedthat withllink 66in the dotted line' positiom the roller I 62. is close to the right-hand endiofislot- I03. The position-of the cran-kiarm 6 I= secured' to the. throttle crank shaft. 68 has bteensu-b'stantially; advanced in .arclockwisedi-1 rection without; any corresponding movement of the :triangular crank arm 65.

The :amount oflost motion-within which the throttle: motormay-adjust theposition of crank arm: 58 variesdepending;upon thesposition of the cranki arm65 onthe inputshaft 58. When the triangularzcrank arm isin the extreme: throttl'e: closed.- positionqshown in- Figures 1 and'3,

-- there .is no lostrmotio-n betweenlink 66-and crankarm 65, as previously explained. As the crank arm 65 is rotated in a clockwise direction so that the roller I! rides outward on the horn I05, the lost motion increases as the-distancebetween the horn adjacent the spot where the roller I 0I is bearing and the opposite point onthe cam sur-' face I04 increases in the direction of translation of beam- 66. It will be readily apparent thatbefore roller IOI has reachedthe outer portion of horn I05, the link 66 can be moved to throttle open position without any movement of crank arm 65. Since the throttle is already in'partly open position anyhow, the amount of lost motion is only from a partially open position to a full open position. Throughout the rest of the range of movement of crank arm 65, -the motor is able to move the throttle'to full open position. The amount of lost motion through" which the motor is able to operate the throttle, however, is continually decreasing since-the-open position to which the crank arm 65 has forced the valve is continually increasing so that the distance be:- tween the manual position of-th'e :v'a'lveland full open position is decreasing continually." When the throttle lever reaches'full throttle open position, even though the roller I02 is atathe lefthand end of slot I03, itis impossible for the throttle motor to move the throttle for the simple reason that the throttle is already in wide open position and the throttle l'ever is' in engagement with stop means (not shown). Thus, the linkage mechanism provides for arange of automatic adjustment which increases from'aimi'nimum to a maximum at some intermediate position of the throttle lever and then graduallydecreasesjto a minimum as open positionfof the throttle is reached. This is graphically shown in Figure '7 and will be discussed in connection with that figure. I 1: 1 1 x In Figure 6, the link 00, the crank arm-65, and the crank arm 6'! are shown in solid lines in the positions in which they'are'illustrated in dotted lines in Figure '5. In ,other words, the throttle motor has advanced the link 66 by reason-of the lost motion existing between roller I02. andslot I03 beyond the position called forv by .the crank arm 65. It .will' now be assumedthat, the crank arm is'rotated ina counterclockwise direction a to close the throttle despite the position of the throttle motor. Upon the' crank arm .05-being rotated in a counterclockwise direction, the roller. IOI is brought into engagement with the cam surface I04 as shown :il'l dottedlines. Simu1taneously, the roller I02"is'brought-into:engagee ment with the right-hand end of slot I03 although the operation,doesl not'irequire such engagement. The parts thus "assumeathe position shown in dotted lines in Figure; 6;. L If ;some means were not provided for tak'ingyup thelost motion between roller I02 and-1 slot, I03, continuous counterclockwise. movement-of crank arm 05 would result in the throttle beingat-itsintermediate position when the-throttle lever 5| was finally moved to; throttle closeqposition. With my linkage, however, the amount of lost., motion between roller I02 and the slot 103,15 taken up as the crank arm 65 is rotated.;...This;is due'to the cooperation between roller IIlI and cam surface I00. As the crank arm, 051s rotate'din a counterclockwise direction thej roller l0] rolls inwardly on the cam surface I04 until it finally reaches the position shown in Figure .3in which the roller I0! is in engagement, with the base of the horn. During" this movement, the roller I02 is moved along the slot 1,03 fromjthe position shown in dotted lines in F-igu're fi to the position shown in Figure 3. In other words, the roller I02 has moved through nearly two-thirds of the distance of slot I03. With my novel linkage, it is thus possible to manually'move the throttle from closed to open position and back toclosed position by providing a range of lost motion dur-' ing intermediate positions of the lever, which range of lost motion in'no way interferes with the relation between the throttle position and the throttle lever position when the throttle is v in either open or closed position.

As previously referred to, I have shown in Figure 7 graphically, the relationship between the position of the throttle, the engine speed, and the manifold pressure with respect to the angular position of the manual control. In the case of the propeller speed, it will be noted thatthe speed decreases from a value of approximately 1800 to a minimum of between 1300 and 1400 revolutions per minute. Thereafter, it increases gradually over a curved line up'to the maximum speed of 2500 revolutionsper minute. Theminimum point at which the speed is between 1300 and 1400 R. P. M. corresponds to the point at which the roller III' is adjacent point a on cam 12. i I I V The manifold pressure initially increases from a minimum of approximately 8 inches of. mercury to 28 inches. This is accomplished whilethe roller I26 is traveling over the steeply curved pore tion of the left-hand end of camslot 'I2 .5 of cam 73.

as being fromapproximately 25 degrees-'to--,a' 1'aproximately 45 degrees of angular movement of the manual control. Starting atabout 45 degrees, the manifold pressure startsri'sing slowly and finally at a point corresponding approxi.

mately to 53 degrees, the manifold pressure starts rising rather'rapidly up to 46 inches. 1 v

Referring now to the action of :thethrottle, it will be noted-that the'throttle opens at arelatively slow rate up to ,40 degreesf In thelchart,

the opening movement of the valve is, ind ated r by the lowermost dotted line. The initialfportion of this line appears in the chart tojbe a straight line although in actual practice as sinusoidal. Due to the slight curvaturej however, it is not apparent on the chart At an angular position o'f 40 degrees, the uopeningfof the throttle follows'a somewhat steepe'rsinusoidal curve. The two ranges of curvature corresponds to those produced when the movement of link 06 is due to the engagement of rollerIOI with horn I05 and that when roller I02 is engaging'the left-hand end of slot I03. The two stages. of movement areso selected as to give an opening of the throttle with change in position representing the relationship between throttle position and flow. Thus, with my apparatus, a uniform change in angular position of the manual control tends to produce a uniform change in the rate of flow. v f

Considering now the closing movement'of the The manifold pressure is-then maintained constant for a short distance, shown in .thechart its maximumvalue of j throttle by the manual control, .which .is indicated :by the uppermost .dottediline, :it will the noted'that the throttle remainsinopen position until the manual control has been :returned to a position of approximately 34 degrees. This stageoimovement of themanualcontrol corresponds to that in which the roller IflI is being ca-rried downinto engagement with the-cam surface, I84. Thereafterythe throttle is:r apidly moved towards closedposition, this motion being produced by the .roller .I'flI moving over the cam surface I84. The areaenclosedbyzthecurve representing the 1 movement of the throttle towards open position and the .lines representing the movement of the throttle towards closediposition is'the area within which the automatic control means can adjust the position; of-the'throttle. As was pointed .out in connection with a :description of 'Figure 5, the 7 range of automatic :adjustment' increases from a minimum to a maximum at approximately 34;"degrees andzthen grad+ uallyzdecreases up to the end of the range of throttle movement. 7 I

OPERATION Operation of control networks Before proceeding with the description of the entire'systern, the operation-of the control "networks for motors53 and 280wi11 first be described.

As previously explained, the winding :88 of throttle-motor -63 is connected through a condenser to line wires Ill and I12. The other winding of the motor is connected to the amplifier I78. Due to'the condenser I I5, the current through winding 88 is'displace'd 90 degrees from the'phaseposition which it would otherwise assume. The amplifier I18 isadapted, depending upon the phase of the signal voltage supplied to it'to supply current to winding 89 which is either 90 degrees behind or 90 degrees ahead of the current supplied to winding88. The input signal voltage supplied to amplifier I18 is determined by 'a-;plurality ofnetworks connected in series with'the input terminals, all'of'which have been briefly described. Proceeding from the input terminal 'I8I a circuit can be traced as-follows: through conductor I84, the-throttle motor rebalancing network I98, conductor "800 network 240a, conductor '50 I switch 255a, conductors "582 and i503, network 123%, conductor 584,1 pressure responsive network I 48, conductor 5115, switch blade I84, contact I65, conductor 506, network 24Ia, "conductors 50'! and 5118, network 243, conductor .509, network 244 and conductor "510, switch contact 292, switch blade *29 I anc l"ground connections 285 and I83 backto'th'e other signal input terminal I82. .All of these various .networks are connected in series between the input terminals and the amplifier. It will'be noted thus, the voltage applied to "the amplifier is equal to the algebrai c sum of thevolta'ge outputs of these various networks. In a condition of balance, 'the'total voltages are equal to zero so :that no input voltage is applied .to 'thexamplifieriand hence no current is supplied to .the amplifier winding89 of the motor 53. The various transformers ,forming units .of the several networks have. suchla phaserelation with respect to each other .that .during any giuenihalfcycle, the ,polarity of the. lower ends .of all the verticallydisposed secondaries with respect .to .theirupper ends is exactly the same as thatof .the leftehand ends of all the horizontally disposed secondaries with respect totheir right-hand ends. To .un-

(lei-stand the voltages appearing acr ss th various. networks, let-the condi i ns b id r d, during whichithelower terminals of all vertically disposedsec ndariesa ep sitive with respect to their upperendsand the left-hand terminals of all the horizontally disposed secondaries are positive withrespect 'to their right-hand ends. Consideringfirst :the'follow-up network I98, it will be noticed .that conductor I84 is connected through conductor I85, slider 98 and conductor mute the left-hand terminal of secondary I88. This left-hand-terminal of secondary I88 constitutes gone-of the output terminals of the network, to which conductor .500 leading to ne work 248is connected. Thus, no voltage whatsoever appears hetween conductors I84 and 580.

Considering now-the network 248, it will be notedthat theslider 267 Qccupies a position substantially corresponding to the position of a tap:;2li9 :ofsecondary 3264 to which conductor 508 leads. 'I'husthesliderZG'I .is at the sa trical'potential ras-ztapy269 so that no voltage is introduced :byrnetwork248.

Considering -.therhext:network 238a. .itwill be noticedrthattheconductor 583 extending to the network.isconnectedttothe positive terminal of secondary 2.5.8 (still ':considering the conditions during a given half .cycle). .The slider 248 is, onthe other. hand,'p.ositioned.half way along the resistor 247. Thus, the conductor v503 is .at :a positive potential withrrespect' to conductor 584.

The/conductor 15.04 is in :turn.:connected tothe lower terminal :of secondary I158 of network 148 while conductor 35.0.5. leading from network I48 is connected-to the'slider. I 4:5whichis at the bottom of resistor I41. T1'lli8, l'l0 volta e is introduced by network I48.

Proceeding through vfconductor 585, switch blade I64, contact I65 and conductor 506, the nextmetwork iniithe group .of series connected networks is network-124m. In the case of this network,"conductor-.506 is connected to slider 214 which is:considerably negative with respect to the lower terminal of .zsecondary .213 to which conductorill'l-is connected. .Thus, the effect of network 210"is ,to introduce a voltage tending to render conductor BUG-negative with respect to conductor 5M, It wi'lltbe noted that the polarity of this 'voltagels opposite to that of the voltage'introduce'd :by network 239a. The voltages applied :to' these'qrespective networks are such that the voltage introduced by network 24Ia is exactly equal :and: opposite to the voltage introducedbynetwork'it'lla. Thus considering all of the networks 'so far, the conductor 501 is at exactly the same-potential as conductor I84 connected"to"the am-plifier terminal I 8 I Proceeding further through-the compound net'- wor-kdformed 'by the group of series connected netwoiks conduetor 501 is connected through conductor- 588 to the upper terminal of secondary 216. "The s-liderj'2i8fis shownin a position at which it is at *the same potential as the upper terminalof secondary 27-6 so that no voltage is introduced pbynetwork .243. The slider 218 is connected through conductor 589 to the lower or positive termi filcni resistor 28L The slider 28'! is positicnedadl'acent' this terminal .so that the slider is .at the same p tential as conductor 509. no volta eis introduced by network 244. Proceeding nowiromslider 281, conductor 51o connected.tolitlislconnected through the switch 7 288 andgrcnnd connections 295 and 2I6 to the other input terminal I82. Q'Ihus, the voltages across the various networks connected in series between input terminals I8'I and I82 of amplifler I18 have a total effective value-of zero. Under these conditions, no current is supplied to amplifier 39 so that motor 53 remains stationary.

Still considering the conditions during the same half cycle, let it be assumed that stem I35 moves upward due either to the manifold pressure within housing I31 dropping or to the spring supports I30 and I3I being rotated upward and together to increase the spring tension exerted by springs I32 and I33 on stem I35. The effect of such upward movement of stem I 35 will be to cause an upward movement of slider I45 with respect to the resistor I41. This will result in slider I45 becoming negative with respect to the lower terminal of secondary I50 and hence with respect to conductor 504. The eifect of this upon the voltage applied between terminals I8I and I82 will be to cause terminal I8I to become positive with respect to terminal I 82. In terms of alternating current, this will means that a current of a predetermined phase is supplied to input terminals I 8| and I82 and hence to the motor winding 89. The operation of the motor 53 will be in a direction to cause clockwise rotation of shaft 92 and, if permitted by the link 69, clockwise rotation of throttle lever 80 to move the throttle towards open position. Such opening movement is, of course, desirable, either where the manifold pressure has dropped or where the springs I32 and I33 have been adjusted to call for a higher manifold pressure.

The movement of shaft 92 in a clockwise direction causes clockwise movement of wiper arm 98 with respect to resistors 99 and I99. This will cause conductor I85 to assume a potential negative with respect to the left-hand terminal of secondary I88. The eifect of this is tooppose the unbalance voltage introduced by the reason of the upward movement of slider I 45. At the same time, the increase in manifold pressure causes slider I45 to move downwardly. After a predetermined movement of slider 98, the voltage introduced by network I98 will be equal and op-- posite to the reduced unbalance voltage so that.

the input voltage to the amplifier will again be zero.

While my invention broadly contemplates the provision of a'follow-up network, the details of network 98 are claimed in the copending application of Alex B. Chudyk, referred to above. Since an understanding of my complete invention involves an understanding of this network, the operation of the follow-up network I98 will be described. The conductor I84 leading from the amplifier I8I to one of the output terminals of the bridge is connected through the left-hand portion of resistor I09 to wiper 98 and is at substantially the same potential as the wiper. Wiper 98 contacts both resistors 99 and I99 and electrically connects the same across the terminals of secondary I88 in a circuit which may be traced as follows: from the right-hand terminal'of secondary I88, through conductor I96, the righthand portion of resistor I09, slider 98,the lefthand portion of resistor 99 and conductor I90 to the left-hand terminal-of secondary I88. The potential of conductor I95 with reference to the left-hand terminal of secondary I88 and hence conductor 599 is thus determined by the ratio between the portion of resistance Ito the right of slider 99 and the portion of resistance 99 to the left of the slider. As slider 98 moves to the right, its potential with respect to the lefthand terminal of secondary I88 is thus increased.

"be linear.

sistor I09 has a considerably lower resistance,

If both resistors 99 and I00were of the same resistance value, the change in potential would Due, however, to the fact that revalue than resistor 99, the change in potential becomes increasingly less as the slider 98 moves to the right. This will be apparent when it is considered that a change in the position of slider 98 not only changes the relative proportions of the resistance on the right and left-hand sides of the slider between the terminals of sec ondary I88 but also increases the total resistance between the terminals of the secondary. In

a typical installation, the resistors 99- and I99 were 700 and 300 ohms respectively. With the slider 99 in the position shown, the resistance between the opposite terminals of secondary I88 is only 300 ohms. With the slider 98 in the oppositeposition, the resistance is 700 ohms. The current flowing through the portions of resistors 99 and I09 in series with secondary I89 thus decreases as the slider 98 moves to the right so that the voltages on the right and left-hand sides of linear effect corresponding to the non-linear effect on flow resulting from a uniform angular opening of a butterfly valve such as throttle 31.

With such avalve as throttle 91, the initial opening movement of the valve produces a rapid change in the flow while as the valve approaches open position, the change in flow of a uniform angular change becomes increasingly less. While I my invention broadly contemplates such nonlinear movement of the throttle, with the improved network I98, this non-linear movement is accomplished electrically in that the voltage introduced into the amplifier network becomes increasingly less as the throttle is moved towards open position. Thus, during the initial opening movement of the valve, only a very slight change in valve positionproduces a voltage sufficient to balance a signal of predetermined strength while during the later stages of movement of the valve, an appreciable movement of the valve is necessary to produce the necessary balancing voltage. I

In the operation above, the effect of movement of the pressure controller arm I45 upwardly was considered. It would, of course, be obvious that a downward movement of the arm has the opposite effect upon the polarity of the voltage applied between terminals I8I and I 82 and hence causes the current to be supplied to Winding 89 which is opposite in phase to that considered before. This will cause opposite rotation of the motor 58 to move the throttle 3'! towards closed position. At the same time, the slider 98 is moved in the opposite direction to supply an opposite rebalancing voltage to the network. Thus, considering only the operation of the pressure controller 52 the eifect of a change in either the manifold pressure or in the setting of the com troller is to cause a change in the position of the throttle 31 of a magnitude suiiicient to produce a change in flow proportioned to the change in manifold pressure or to the change in spring tension of stem I35. The operation of this pres- .Surecontmlller will be referred to again inconnection with the waste gate .motor 290 and in connection with. the.system..-.as a whole. I

.Theoperationlof networks 239a, 240a, 24m, 253, and244 will berconsideredlater after the operation .of the network: controlling thewaste gate motor;2 ll0. is considered. .At the present time, it may Joebrieflywpointedom that adjustment of any of these sliders will produce a variation in the position of the throttle maintained for a givenposit-ion of the slider I45 of the pressure responsive apparatus.

. Referring now, totthe' wastegate motor 288, the winding 202 .is, as previously pointed out, conn cted throueh the condenser 20'! to the line wires Hi and [1.2. This winding is thus constantly energized with the current. displaced :in phasej90 degrees with respect to what its phase position otherwise would .Joe. The winding 203 isconn ct dr to. the outputterminal of an amplir ductor 1586,:pressure responsivernetwork 1 58., condoctor-i525,uswitchi blade 164, contact I55, conductor $0.6, network 241a. conductor .5077, network 243,...onductor3509;..network 244, conductor 5 I:B,=swi.tch 290, and-ground connections 5295 and H6 back tofthe other input terminal 215. It willbe noted that the compound network just traced'included thenetwork 239a and the pressure :responsive network I48, previously considered. The. pressurecontroller 52-tbus controls not only the throttle motor 53 but also the waste gate 'motorr2'00. As will be clear from the later description, .upon a continued demand for increased manifold pressure,'the throttle motor is first moved to open position, and thereafter the waste gate is moved towards closed position.

As uvith' the various networks of the throttle motor compound network, the polarities of the left terminals of the horizontally disposed secondaries are always the same with respect to the right terminals .of the secondaries as those of the lower terminals of thevertically disposed secondaries with respect to their upper terminals. Considering now the conditions existing during a half cycle in which the left-hand terminals of all o-frthe secondaries and the lower terminals of all of the secondaries .are positive and proceeding from .input terminal 521.4 through conductorrzdz, it willsbe noted that slider M9 isat the extreme le-ftehand'end ofresistor 220 so that the conductor'242 is at the same potential as tap 236. Similarly, slider 2:29 is atthe right-hand end of resistor-;22.1 to he at:the same potential .as tap 23:5,. ilhus. conductor-2:42 is negative -with .-:ce heet-to =conduc-to.r .i5l5 by the amount of :the voltageexistingbetween taps2135 and 236. The conductor 5151's in turn connected through conductor-.593 to thezlower terminal of secondary 251 of network 23811.. .It will be noted that the slider 248 is negative with respect to the lower terminal'of secondary .so that conductor 5.83

CTl

' and hence reducetheunbalance voltage.

tendsto ..be.;rendered positivewith respect to slider 24.8 and hence with respect to conductor 5%. The voltage introduced .by-network 239a thus opposes that introduced by network .23 i. In actual practice in a typical installation, the voltage introduced by network 239a is greater than that-between tapsx235 and 236 and hence introducedloy network 23.]. Hence, the conductor .242 connected to input. terminal-2M is positive with respect to conductor 504.

Proceedingjnow to the network .143, the slider 505 .isatthe .lowerzend of resistor 14'! so that the potential introduced thereby is ne ligible. From slider ill-.5, the circuit proceeds through conduct-or 5.0.5., switch .H54 ,.:contact 1'65 and conductor 5B6 tothe. network: 241a. The Slider. 274 is negative with respect to the lower endof secondar 273 to which conductor .50! i connected. Thus, the voltage introduced bynetwork 24m opposes th introduced by :239aiasnd aids that introduced by network 23].. .Inthe typical installation-referred to above, withthe sliders .in the p s tionshown. the voltageintroduced .by..netwo.rk 24m exactly balances that introducediby network 239a so that conductorofil is eta positive potential With-respect to conductor- 242 by a voltage correspondin to the voltage existing between taps 235 and 2316.

Proceeding from network 24 l a, the. circuit .extends-througheonductors 15261, 08, network 243, conductor 509, network 244, switch 2.96 and ground connections '295.a-nd .216 to the other-in put terminal. It will lbezrecalled that :no voltage exists acros the output terminals of either networks .243 or244. v.I-Ienee,:.:ero-1.1r1d connections 2-95 and 2l6 are atthesame-potential as .con duotor =ollfir-whichit-wiil he recalled is positive with respect to conductor =.2.3-I connected to the terminal 214. Inother words, terminal 214 :is negative with respect to'terminal 215. The effect of this volta e on the-amplifier 2H is to cause current to be supplied to motor winding 2% of such .a phase as toeauserotation of motor 20.0 in zaidirection to .moverthe waste gate towards open position, 'Ihe waste gate tll :is already in open position and the crankarm222 is prevented from further opening movement-by stop 223.. A suitable slip clutch (not shown) is provided :between the motor and crank-arm 222 to prevent injury ofthismotor under these conditions.

vI-zf under the conditions iustconsidered, the manifold pressure drops sufiiciently .or the setting of the pressurecontroller .is raised sufficiently to cause 'an upward -.movement of slider M5 to a point withrespect'togresistor M! in which the voltage between .the ::slider I and the lower terminalof secondary lsdflexceeds'the voltage between. taps 23;.5wandi 2.3.6, the terminal '2 It will no-ionger :be'nega-tive with respect :to terminal 215 .duringrtheconductive -half cycle being considered. The phase of :the current supplied to winding {2-113 will'then be reversed and the motor will rotate 111a direction to cause closing-movement of the waste .zgete 2.0.. "This will .cause move ment of slider. .2I'9: to the right to introduce into the series connected networks a voltage opposing the unbalance voltage introduced by the pressure responsive network M8. The closing of the waste gate will increase the manifold pressure to decrease the voltage across network I48 After a predeterminedmovement of the waste gate, this reba-lancing voltage will equal the reduced unbalance voltage andthe. series of networks will again be rebalanced to .cause xdeenergization of themotor 2:00. Thisoperation of the waste gate 25 motor does not normally occur, however, until the throttle motor has moved to a position at which the throttle is substantially open.

The operation of some of the controllers of the pilots control unit 53 will now be considered. The networks 243 and 244 are employed to vary the manifold pressure for the two engines being controlled. For the present, the effect on only the illustrated engine will be considered. These two networks constitute what may be referred to as the manifold pressure selector. The sliders 218 and 281 are normally moved through a range of movement which carries the slider 218 over the full length of the resistor 211. The range of movement during which slider 281 moves over resistor 28I is employed only in emergency conditions where extremely high manifold pressures are desired. This range of movement provides manifold pressure which cannot be maintained for long periods of time without severe damage to the engine.

Considering the operation during the half cycle which has been used for illustrative purposes throughout the specification, that is in which the lower ends and the left-hand ends of all secondaries are positive with respect to their opposite ends, a movement of slider 218 downwardly with respect to resistor 211 will cause conductor 588 to become negative with respect to slider 218. Since the slider 218 is connected to ground through conductor 589, slider 281, conductor 518 and switch 298, it will be obvious that the effect of causing conductor 588 to become negative with respect to slider 218 is to cause the ungrounded input terminals I8| and 214 of amplifiers I18 and 2 respectively to become less positive or more negative with respect to the grounded terminals I82 and 2I5 respectively than was previously the case. It will be recalled from the operation described above, that in the case of either amplifier I18 or 2, a change of the polarity of the ungrounded input terminal in the negative direction tended to produce a movement of the control device positioned by the associated motor in a direction to decrease the manifold pressure. That is, in the case of the throttle motor 53, the amplifier I18 tended to so energize the throttle motor as to cause it to move the throttle towards closed position. Similarly, in the case of the waste gate motor 288, the effect of changing the polarity of the ungrounded input terminal 2 M in a negative direction with respect to the grounded terminal is to cause the motor 288 to be energized in a direction to drive the waste gate towards open position. Thus, as slider 218 is moved downwardly with respect to resistor 211, the effect of such movement is to cause the waste gate and throttle to assume positions such that the manifold pressure is reduced. The lowermost positions of slider 218 with respect to resistor 211 may be referred to as constituting the approach and preflight range. The slider 218 is shown in its normal position.

If the sliders 218 and 281 are moved upwardly to the point where slider 281'moves over resistor 28l, the conductor 589 which is connected between resistor 28I and a conductor bar 286 becomes positive with respect to slider 281 which is connected to ground, as previously explained. Thus, the efiect of movement of slider 281 from the position shown is to increase the polarity of ungrounded input terminals [8! and 2| 4 in a positive direction with respect to the grounded terminals of the respective amplifiers. This tends to cause the motors associated with these ampliflers to so position the associated control devices moved over the resistor 28l.

as to increase the manifold pressure. Thus, a movement of slider 281 upwardly with respect to resistor 28l raises the manifold pressure. As previously explained, slider 281 is normally not This range of adjustment is used only when an emergency condition exists requiring the maximum output of the engine even though this output is greater than can be maintained with safety for any appreciable period of time.

The networks 24m and 24lb are provided for individually adjusting the manifold pressure of the two engines. Both conductor 581 leadin from network 24m and conductor 581b leading from network 24 lb are connected to the networks 243 and 244 so that, as previously explained, the adjustment of the latter two networks controls the effect of both engines. Considering the network 24la which is associated with the engine illustrated in the drawing, it will be apparent that a movement of slider 215 upwardly tends to cause conductor 588 connected to the slider to become more highly negative with respect to conductor 581. This causes change of the polarities of the ungrounded input terminals I8! and 284 of the two amplifiers in a negative direction with respect to the ungrounded terminals so as to cause a reduction of manifold pressure. Similarly, a movement of slider 214 downwardly with respect to resistor 215 increases the potential of input terminals 18! and 284 in a positive direction and causes the manifold pressure to rise. Thus, the adjustment of the slider 214 causes the manifold pressure to be adjusted independently of the setting of the lever 5 I. The potentiometer 212 is thus employed to individually adjust the manifold pressure of the engine shown independently of the position of throttle lever 5| and is referred to as a manifold pressure Vernier potentiometer.

Proceeding back to the positive terminals of the amplifiers, conductor 586 leading from the slider 214 of the manifold pressure -vernier extends through contact !65 and switch blade I64 to the pressure responsive network, the operation of which has previously been considered. From this network, a conductor 584 leads to the networks 239a. Considering the operation of the potentiometer 248 of this network, it will be apparent that a movement of slider 248 upwardly causes the ungrounded input terminals of the two amplifiers to become more positive with respect to the grounded input terminals and hence to cause the manifold pressure to be increased. Conversely, a downward movement of slider 248 causes a decrease in manifold pressure. The potentiometer 248 thus is similar to potentiometer 212 in that it individually adjusts the manifold pressure for the particular engine with which it is associated. The purpose of providing both networks 288a and Mia is to provide for independent calibration of the system at different positions of the throttle lever 5|. The network 238a is employed for calibration purposes when the lever 5| is in the position assumed when the airplane is taking off or what may be referred to as the military power position. The potentiometer 246 is thus referred to as the military power calibrator.

The networks 243, 244, 24m and 239a, together with the pressure responsive network I48 are all common to the series of networks associated with the throttle motor amplifier and with the series of networks associated with the waste gate motor amplifier. The remaining networks to be considgiven se t n o he-other o rols- If slider 261 tent ometer 2. of thi net or s moved up, the fi t will e oincrease n a positive direction the potential of input terminal I;8;I of ami r H th ms eQt Q-t e r unded n t minal I82; m tn rtworcs, with slider 261 m e s tion shown. 1. 9 qitas i n r u d into hel mttl' mote am liilsrwssr s f.- networks, s-" ter qus r e. allied. W t he. li 26? oved-unhow v r-1 he-Potentia Q ndu 5 as e celoi nr t e m nal J increased in he;nes tivadireqtio esv t r o explained, such. movement. tsndste en movessntd thethrqt le. Qbv quslrr o q m n idtl Z61 ausem o n mov m ntof hehrottle; f It; t 9i ebernqted a sincethis newest .n' t. cqene ted n eries. withthe input er iinals thei a ts eatsm pr mp the hunbr. 9 n 1i e 1 the ontlist rot le andwa t ga canbe changed Itis 1 often; desirable H to have hi'waste sa epar-t wlq edev nwh n t r e s. noti ilr p n n rder l e h t r; ompre sion tor. l at nsth sar re Fu he nere. hear iu tsisn ro d d; po te -2.63 t qs i lsil c a ibrate he 535" en he-instills n. r isin position, as will be exp dv i more detail; later. i For. this 's tfilin .9 eter an elr t r to as he ru seal tors:

h sr f; stworks or he. thr t m t mpl fi 1T8 1 m ludest e'fqllow p e w IQ8,-pusly iscussed It not belieyed that N ey i rth i i t. sipn f. his" e w h is necesart;theptesent ima.

nside insr ewr he s r n. e or s co necte he Westesatean e h operation Qf-" he 'n'etwo as. ee: e.sc b d o. :f as et on-ofio ow-upot icmete I SxXm-v cffidi onstan -se es hews ree o enometerhei neri Z. as previouslrstated, nor-ma s: he I Y att ns; i ht-hand. position hown hefira ingm ponl he. cu ren -ti e-pr mised wti i rhow ve e spe controller Z IILis operati e .to ,movethe wiper 229 to. the left. Such movement to the left tendsto cansel conductor 242 to..be morenegative with p ctto on or 15.... hus. hepolar ty of p t term all I 4 o mplifier. 2 I smade' o negative with respect to groundedterminalilfi', or if the terminalis already positive with respect toterminal 2I5; is made less positive; The result is-that the motor-200 tends torotatethe waste gate open directionto reduce the speed of the turbine.- Since the purpose of the overspeed controller 240 .is. to preventan excessivenspeed' of.

the turbo supercharger it is.-obvious1y;u-nneces.

sarrtohavethis. control a i ctthethrottle m0t0r.:..

itnhea pve explanationpitheznormalon: v ationnfrt n hro e mo or 31. an hewa ie... te 91 9 0.a. .;m. n s 9wssibl to explain broadly the normal operation of theisyse tem, Various checking features are. provided and for the present th fiwill beienmfd- Operation of entire system With: e d m its.i tzt ee os tien sho n-i ures and 4 .1% :thsq t e. i omnl r se id ;e .ee -w at o ver on and i the waste gate iSrWid-fit open. The throttle lever-SI has been movediq.- i-ts: extreme. minimum power position which is atrthe: lower end of what may bereferred-tog as the.-'Idle' Range. Assuming the plane to be, on. the: ground in order tostart the engine.itisnecessary;to slightly open the. throttle, Thisr is done.- bv -a slight movement of lever 51 in a clockwise. direction- Such. clockwise movement ofthe lever .5-I- causes alt-clockwise movement ofshaft 5.8' and a; clockwise; movement of-cranlg arm 65,110... in. turn. cause; a clockwise movement of shaftta-and throttle crank :arm: 89, allas previouslyexp-lained. Such, movement of the throttle crank; armi30=causes the thtottle 3I to bermoved towardsaopen, position. The, clockwise rotation. of shaft58; also. causes a. clockwise rotation of cams I2 and 13.. The-slight: clockwise rotation of 0am I 2r causesa-slight movement. of the propeller governor pulleyt lfi a counter.- clockwise, directionto decrease: the. propeller speed.

The movement-of; cam: 13in. a. clockwise.-. direc tion, causes a; counterclockwise. rotation of crank arm; I21 to swing thespring supports l:3.0.and- I3I- upwardly. This, has-. twoa effects. In. the. first placer the, spring; supports. are; moved away from the-leafspringfifl so that..there is no.v longer. a relatively. rigid mechanical. connection: between thecrank arm. I21 andfltheastemswfiz. At-the same time, thetensionexertedbysprinsssltzand I33.on.the.stem I351-i's,increase.d so. asto. tend to cause. an upward movemennofi.stem,.I3.52 This;v as previously explained-. causesgan, upward move-. ment. of slider Idi lwith, respect to.- resistor I41. Such an upward. movement. tends. towcause; the. throttle motor 53 to be energized. in; a .direction. to drive the shaft 92.,inthrottle opening, direction. Since it. is. normally desirable, to, have: manual; control of the throttle at this time theslider 218 ofthe manifold pressure selector, is moveddownwardly withrespect, to resistor 2..'I"I- bef0re.throttle lever 5I- is movedtowards openpositionh Thusdespitethe movementof, thelslider, I-4.5. of the. pressure responsive network the. throttle. motor v willstillremain deenergized, or. energized. in a. throttle closing direction, In. such case, the. throttle is. positioned. entirely manua11y,. the. strain release clutch permitting, the .relative slip.-- page of shafts .58 and.92.,

With} the.- en ine. started. various. checks are. made to insure proper operation of the. enginen the. pmpeller, governor, and the. control apparatus. of. the, present. invention... These :various ,checks.v will be referred to.,.later. Assuming.. that the. engine hasbeen properly warmed. up..and that. the.

ship is ready for.the.take=off,.the.s1ider.2180f the.

manifold pressure,..se1ector..isrset, to the normal. position, whichis substantially .that shown .in .the drawing, The throttle. lever 51-" .is thenmovedto. its extreme rightzharidspositionrto..movethe-elsements of. the. coordinatorto. .thepositibn shown. in Figure 4 which. may. be referred l, to a as themilitary power or ,takeeofi'positionl Suchmove: ment results in. suificient manual-clockwise .rotatiQnof shaft .68to.causethezthrottlestolbe moved I to theirwide. open position. At;the.,same..time,., the propeller g'ovemor, I2 "isrotatedito; apoint at which ro1le1'; III.is' at theend- .of..the..cam. slot III! opposite tothatjin whichitis shownin Fig-.- ures 1 and 3;}. Atgthisisetting thepropeller gov, ernor calls for.take.-.0fi .j speed;j.

This movement. of the. .throttle...lever .5 I.) to:. its. extreme right-hand-position also causestheprese sure "controller. cam. .7 3-?to, .he. rotated .to' a posi.-' tion in.v which the. roller. .I261 "is at the. extreme,

:end. of. slot. '..I 25fopposit'etd thatginjwhich'j itisl.

shown. This brings the springs I32 and I33 to a position in which they extend substantially vertically so as to exert their maximum effort upon the stem I35.

The rotation of the crank arm I21 by the cam 13 also results in cam I62 being rotated to a position in which the pin I63 is moved to the right by the cam to cause switch arm I64 to move from engagement with contact I65 into engagement with contact I66. The effect of this switch is to remove networks 24Ia and 243 from the connections to both the throttle motor amplifier I18 and the waste gate motor amplifier 2. The range within which the cam I62 is effective to hold switch I64 in engagement with contact I66 is the military power or take-off range. During this range of powers, it is highly essential that the power be limited essentially to that selected by the throttle lever 5I. If the power under these conditions can be effected by the networks 24Ia and. 243, a previous faulty adjustment of these networks may result in inadequate or excessive power during take-off conditions or at other times when military power is needed. When switch blade I64 is moved into engagement with contact I66, the input circuit to amplifier I18 becomes as follows: from input terminal I8I through conductor I84, follow-up network I98, conductor 508, network 240a, conductor 5III, contact 258, switch blade 256, contact 25I, conductors 582 and 583, network 2390., conductor 504, pressure responsive network I48, conductor 5B5, switch blade I64, contact I66, conductors 528 and 52 I, that portion of secondary 282 of network 244 between taps 283 and 284, slider 281, conductor 5"), switch 290 and ground connections 295 and I83 to the inputterminal of the amplifier I18. It is to be noted that the circuit just traced does not include the manifold pressure Vernier potentiometer 212, or either of the manifold pressure selector networks 243 and 244, with the sole exception of a fixed portion of the network 244. The voltage between taps 283 and 284, in one particular embodiment of the invention, corresponds substantially to the voltage between slider 214 and the lower end of secondary 213 of network 2'4Ia, when the slider 214 is in the position shown. Thus, the portion of secondary 282 between taps 283 and 234 introduces into the system a voltage substantially the same as introduced by network 24Ia when the elements are in the position shown. This voltage is one which gives a normally desirable manifold pressure, since original calibration was made with it in the circuit.

The movement of switch I64 from engagement with contact I65 into engagement with contact I66 also alters the waste gate network by the elimination of the manifold pressure vernier networks and the manifold pressure selecting networks, except for the fixed portion of secondary 282. Considering the circuit between the input terminals 2 I 4 and 2 I 5 of the waste gate motor amplifier, a circuit may be traced from the input terminal 2I4, through conductor 242, the followup and overspeed network 23I, conductors 5I5 and 583, the military power calibrator network 239a}, conductor 584, pressure controller network I48,-conductor 505, switch blade I64, contact I66, conductors 520 and 52I, the portion of the secondary between taps 283 and 284 and back to the ground connection 2I6 through slider 281 and switch 280 as previously traced.

Thus, by the provision of the military power switch I64, and the circuit connections associated therewith, the power during take-off is determinedentirelybythe throttle 5I except for the overspeed controller 248, the'cruise calibrator potentiometer 263, and the military calibrator potentiometer 246.- The military power calibrator is, however, relatively inaccessible and is normally not available for easy adjustment by the pilot. The cruise calibrator potentiometer only controls the position of the throttle which under these conditions is wide open regardless of how the cruise calibrator potentiometer is set. The overspeed potentiometer is operated only when an overspeed condition exists and is necessary. Thus, the power supplied by the engine within this range is subject to rather close control bythe throttle lever 5|. It is being assumed in connection with the description of the operation under these conditions that the slider 281 ,is not in engagement with the resistor 28I, or, in other words, is not moving into the emergency range. If the slider is so moved, the manifold pressure is, of course, further increased in accordance with the position ofslider 281.

Afterthetake-ofi, the throttle lever is slight- 1y retarded so as to reduce the propeller speed. At take-off, the propeller speed may, for example, be 2500 R. P. M. After take-off, this speed is reduced to 2300 R. P. M., for example. This movement of the throttle 5I will bring it to what may be called the rated power position and will cause su'filcient counterclockwise rotation of cam I62 to allow switch blade I64 to return to contact I65 thus restoring control of the manifold pres sure selector and the manifold pressure verniers. The pilot may, if desired at this time, adjust the manifold pressure to a value which he feels is more satisfactory .for climbing. Such adjustments maybe necessary to overcome'instrument variations and other variations in the aircraft equipment.

When theairplane has reached the desired altitude, the throttle lever 5I is retarded to an intermediate position within the cruising range,

Under these conditions, it is desirable that the slider 218 be in approximately the position shown for maximum fuel economy. The position to which the shaft 58 and the throttle crank arm 86 are manually moved is an intermediate position, under these conditions. At any appreciable altitude, however, in order to maintain in the pressure demanded by the pressure responsive controller 52 under these conditions, the throttle motor 53 will have been affected to drive the throttle to wide open position and, in all likelihood,-the waste gate motor 260 will have been affected to drive the waste gate partly to closed position. The further movement of the throttle motor is possible because of the lost motion provided by the slot I03, as explained in connection with Figures 5 and 6. It is to be understood that with slider 218 in the position shown, the throttle motor is always eifective to open the throttle further than it is moved directly by crank arm 65.

As the aircraft changes in altitude during cruising conditions, the waste gate and throttle will beadjusted to maintain the desired manifold pressuredespite the varying-density of the air. In this connection, the feature of bellows I39 is of importance. In any system of a follow-up type such as that employed by applicant in connection with both'the waste gate and throttle motors, it is necessary in orderto get a change in the position of the controlled device for there to be some change in the controlling condition. Thus, as the load increases, it is impossible to maintain the controlling condition at the exact desiredvalue- The only-way to change the con 'trol device to take care of" the cnange lead is for the controlling condition to change itself. Thus, applied t'o-the present case; theonly way in which itispossible to ohta-in settnigs of the throt tle and waste gate toproduce higher manifold pressures is for" thepressu-re todrop. Asthe atmospherio pressure decreases with higher alt-i tudes, an increasing d'rop'irr manifold pressure thus tends to result.- This is" referred trials the "droop of the ystein; A certain amount of droop is not undesirable since with an increas'edn altitude it is" possihlejto drop- -the manifold pressure slightly and" still ohtaiirthe same power. This 'is' due to a decrease in the exhaust hack pressure; An exces'sived'roop-is-, however, ,unde sirab'le; The bellows l 39* tends" to avoid sucnan excessive droop: Astheatmospheric' pressure decreases, the forceopposingitheupward movement or bellows l 36i's decreased, justas though the manifold pressure itself: decreased". conse uent: 1y, for a givenmanifold-pressure; the position or slider I45 is changed in the direction to increase the manifold pressure. Thus; a theatrno'spheric pressure decreases; the setting ofthe'sy'stemis raised for any given manifold pressure: The size of bellows l39-is so selected that when" the-lever 51 is set to its extreme right-handipos'ition to maintain military or takeofi power zthe bellows l39'wil1' provide just enough compensation toolo' tain the desired amount of droop" and constant power. At all settings of the'throttl'e leverf5l, the bellows I39 aids in. reducing the droop:

When it. 'is'd'esired to land, the manirolni ree sure sele'ctor o'r' slider 218 may hemmed-downwa'rdl into the range'l h' which a lowermaniioid pressure is. maintained. This" permit the throttle to be manually controlled without" Being affected appreciably by the throttlehiofor' 53'; The pilot normally considers it desirableito' have complete manual control of the throttleduring the landing, If it happensthatithe l'ane'is go; mg, to overshoot or'undershoot thefiel'dl'so that it is necessary to take on"; the movement'ofthe selector slider 218' to a. lbwmanifbld pressure position does not. presentany hazard." because of the military. power. switch IB'df A'sso'on' as-the pil'ot finds itnecessary to take on? again and moves the throttle lever 5Tto themil'itarypciwer position, Switchblade. I164 is .movedl'into engagement' with contact I S'BI to gilve. fiill powerri'n d'ependently of the settings oflthemanifold pressure selector or the manifol'd'pressure Vernier. as previously explainedl Thus full power is immediately available for take-ofil By retarding the-manifold pressure selector under landing. conditions, it isassured: thatathe manifold pressure will be suficientlyzlowfl-that'the propeller blades. will be maintained 'at-etheinminimum pitch position due: to the slowspeed at which the engine is tending to rotate th'erpropeb lers. This gives the maximum braking? efiect from the propellers. Furthermore-if itv becomes necessary to take ofiagain: so thati-the throttle leverisrmove'dto the maximum-powerzposition at which the: propeller governor: 'is set-tot maintain the; blades; in their minimum pitchpositioni no ch'an'gei in the settings-of the propeller blades is necessary? If the: propeller blades :wereiim ome intermediate pitch pZJSitiQlli during; the landing and iti becameinec'es'sary to take-off, vthere: would be an appreciable d'elay-trequired .for the blade's to change'to' their minimumipitchxpositione'suchas is dsirablefor' take'-ofi.- Byimaintaining fthe mani fold" pressure sufli'cientl filow *torlreepthe bladesm their minimum:pitch p'osittom; thisis'avoldede Inthe above op'eration the operation of the ad j u's'ti-ng mechanism of" the pressure responsive controlhas beenonly -briefly discussed. The par-'- tioular arrangement of the meansof adjusting springs L32 and i323 has'-'certain unique advantages; As the springs I32 and l33- are rotated toa position in which? the springsaremo're nearly vertical, noton'ly is the tension exerted by springs I32 and l'3f3'onthe'ste'm [35 increased but the ene' tive; springrateof these springs, ag'far as the stem leeis concerned; is qal'so increased: In other words, with the springs'in th e position shown; not only do the'sp'rings' exertl'e'ssforce'upon the stem l'35b'ut the amount offoree required tomovethe stem I35" through-a predetermined distanceis considerably less. from the fo rce-re-qoiredi to move" the" stem at all and the-force required to nicvei't through avpredetermineddistance increaseasth'eisprings arerota't'e'd towardsa'vernear position. a As a result, when thespringsrare in: the positi'cnshcwn; a verysmallchange in manifold pressure will make an appreciable change" in the o ition of slid'er ldi. When on the other Hand, the sprin sare in a nearly verstem l35"'t hrough' a predetermineddistance" is much greater. This isimp'ortant becausewhen Hie throttle leveris ifl the advanced of positions, the amount ofmovement-of the'vlfas'te gate necessary to effect a change in the: compressing. effect ofthe compressor is" relatively small because ofincreased volu' meof exhaust gases. In order to'main-tain this ower at any appreciable altitude, the" tnrqtti'eis' wide o en :and' the. waste gate i's probalol y partially closed. Thusthe only adjustment available to take care oflan increased need for superchargingis a small movement of the waste gate necessary to completely-close the same When thethrottl elever is inthe retarded position suchas shown, however,. the available range of control includes. the movement of the th-rottlefrom substantially full closed position to open 7 position and the movemerit of the waste gate from openpositiomto-full closed position;- Unlessa control-is very sensitive underthese: conditions,-- a very suicstant ial dro op: Willoccurs Inother words; asthe planeascends with an increasing demand for supercharging, a. greater and greater drop in manifoldpr-essureisnecessary; to efiect the necessary adjustment oi the waste gate- By reason of my arrangement in which the-control is highly: sensitive at:- the low power settings oi the throttle,v only: a slight change immanifold pressure results: in a -large movementor the control devices-sufficient totake careof a wide range-- of altitude'vari'ati'on-e 7 It will. thus beseen that-I=,- have=providedna system: in which'the sensitivityds varied maccordance' with the necessary: range of adjust ment: to reduce; the: droop to a minimum. I-f when the plane i lvat a=relativelyhigh altitude, it: becomes necessary to start it; the throttle leveris moved back into the: idle position inwhich' it is substantially in the position shown in'Figure' l. The movement of the throttle lever to this position causes the spring supports l3!) and: [31' to be rotated to a; position at which they? engage. the leaf. spring member I33- and force the stem [35 "dOWHW8/ICHY By reason of the leaf spring [33,1 the-pressure controller stem is: forced down much more-thanwould bethe case-otherwise at high altitudes. Normally: at a higli altitude, with the enginesstopped so; that therei's :no '=exhaust;gas;: thelow maniiold pres- 

